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United States Patent |
5,016,438
|
Harris
|
May 21, 1991
|
Emission control apparatus
Abstract
Improved emission control apparatus for use with an internal combustion
engine having a housing with an inlet and outlet, the outlet being
connected to the exhaust of the engine. Mounted in the housing at spaced
locations are first and second catalytic cells through which the engine
exhaust gases pass for conversion to less noxious compounds. Some of the
gases passing through the first catalytic cell are returned upstream
thereof for recirculation through said first catalytic cell. All of the
gases pass through the second catalytic cell.
Inventors:
|
Harris; Harold L. (Houston, TX)
|
Assignee:
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Harris International Sales Corporation (Houston, TX)
|
Appl. No.:
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411818 |
Filed:
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September 25, 1989 |
Current U.S. Class: |
60/299; 422/176; 422/177; 422/180 |
Intern'l Class: |
F01N 003/28 |
Field of Search: |
60/299
422/176,177,180
|
References Cited
U.S. Patent Documents
2288943 | Jul., 1942 | Eastman | 60/299.
|
3180712 | Apr., 1965 | Hamblin | 422/173.
|
3445196 | May., 1969 | Thomas | 422/180.
|
4601168 | Jul., 1986 | Harris | 422/180.
|
Primary Examiner: Hart; Douglas
Attorney, Agent or Firm: Berryhill; Bill B.
Claims
I claim:
1. Improved emission control apparatus for use with an internal combustion
engine, said apparatus having an enclosed cylindrical housing with an
inlet at one end thereof for connection with the exhaust of said engine
and an outlet at the opposite end thereof; converter means being mounted
in said housing for reducing noxious gases emitted from said engine by
converting nitrogen oxides, carbon monoxides and unburned hydrocarbons to
less noxious compounds for discharge through said outlet, wherein said
converter means comprises: a first catalytic cell transversely disposed in
said cylindrical housing at a fixed distance from said housing inlet and a
second catalytic cell transversely disposed in said cylindrical housing at
a fixed distance from said first catalytic cell, the cross-sectional area
of said first catalytic cell being less than the cross-sectional area of
said cylindrical housing leaving one or more return areas which allow at
least some of said engine exhaust passing through said first catalytic
cell to return through said return areas for recirculation through said
first catalytic cell, all of said engine exhaust passing through said
second catalytic cell prior to discharge through said outlet.
2. Improved emission control apparatus as set forth in claim 1 in which
said first catalytic cell is circular in cross-section and is coaxially
mounted on the axis of said cylindrical housing, said return areas being
provided by a plurality of ports radially disposed around said axis
between the outside diameter of said first catalytic cell and the inside
diameter of said cylindrical housing.
3. Improved emission control apparatus as set forth in claim 2 including a
plurality of tubular members, one for each of said ports, extending from
said ports toward said inlet and through which some of said engine exhaust
which passes through said first catalytic cell may return for said
recirculation through said first catalytic cell.
4. Improved emission control apparatus as set forth in claim 3 in which the
walls of said tubular members are perforated by a plurality of holes
allowing some of said engine exhaust to enter or exit said tubular members
therethrough.
5. Improved emission control apparatus as set forth in claim 1 including
noise reduction means mounted in said housing for reducing the noise
emitted from said engine, said noise reduction means including at least
one tubular member in fluid communication with said housing inlet and
opening toward said first catalytic cell.
6. Improved emission control apparatus as set forth in claim 5 in which
said noise reduction means comprises a second tubular member one end of
which receives the converted exhaust gases leaving said second catalytic
cell and the opposite end of which is attached to said housing outlet so
that said converted exhaust gases may be discharged therethrough.
7. Improved emission control apparatus as set forth in claim 6 in which the
wall of at least one of said tubular members is perforated to allow
circulation of exhaust gases therethrough.
8. Improved emission control apparatus as set forth in claim 6 in which a
plurality of smaller tubular members whose axes are parallel to the
central axis of said housing are disposed about one end of said housing
opening into an area downstream of said first catalytic cell and providing
return passages which allow at least some of said engine exhaust which
passes through said first catalytic cell to return upstream of said first
catalytic cell for recirculation therethrough.
9. Improved emission control apparatus as set forth in claim 1 in which
said first and second catalytic cells are of substantially the same
cross-sectional flow area, the area between the outside perimeter of said
second catalytic cell and the inside diameter of said housing being closed
so that all of said engine exhaust is directed through said second
catalytic cell for passage into an outlet chamber and exit through said
housing outlet.
10. Improved emission control apparatus as set forth in claim 9 including
one or more tubular members, one for each of said ports, which extend from
said ports toward said one end of said housing and through which said
returning exhaust gases may pass for said recirculation through said first
catalytic cell.
11. Improved emission control apparatus as set forth in claim 10 in which
the walls of said one or more tubular members are perforated by holes
allowing exhaust gases to enter and exit said tubular members
therethrough.
12. Improved emission control apparatus as set forth in claim 11 including
an inlet tube connected at one end to said inlet and the opposite end of
which opens toward said first catalytic cell.
13. Improved emission control apparatus as set forth in claim 12 in which
said inlet tube is frustoconical the diameter thereof increasing from said
inlet toward said first catalytic cell.
14. Improved emission control apparatus as set forth in claim 12 including
an outlet tube connected at one end to said outlet and the opposite end of
which is open to receive converted gases passing through said second
catalytic cell.
15. Improved emission control apparatus as set forth in claim 14 in which
the walls of at least one of said inlet and outlet tubes is perforated by
a plurality of holes allowing gases to enter and exit said tubes
therethrough.
16. Improved emission control apparatus as set forth in claim 1 including
noise reduction means mounted in said housing for reducing noise emitted
from said engine, said noise reduction means including a plurality of
perforated tubular members upstream of said first catalytic cell and a
plurality of perforated tubular members downstream of said second
catalytic cell and through which said exhaust gases may pass.
17. Improved emission control apparatus for use with an internal combustion
engine, said apparatus having an enclosed housing at one end of which is
an inlet for connection with the exhaust of said engine and at the
opposite end of which is an outlet, converter means being mounted in said
housing for reducing noxious gases emitted from said engine by converting
nitrogen oxides, carbon monoxides and unburned hydrocarbons to less
noxious compounds for discharge through said outlet, wherein the
improvement comprises:
a first catalytic cell transversely disposed in said housing separating an
inlet chamber thereof from a downstream intermediate chamber and through
which at least some of said engine exhaust gases pass;
a second catalytic cell transversely disposed in said housing separating
said intermediate chamber from another chamber downstream thereof and
through which all of said engine exhaust gases pass prior to discharge
through said outlet; and
return means providing fluid communication between said inlet chamber and
said intermediate chamber to allow at least a portion of the exhaust gases
passing through said first catalytic cell to return from said intermediate
chamber to said inlet chamber for recirculation through said first
catalytic cell.
18. Improved emission control apparatus as set forth in claim 17 in which a
transverse wall surrounds said first catalytic cell providing a dividing
wall between said inlet chamber and said intermediate chamber, said return
means comprising one or more ports through said dividing wall.
19. Improved emission control apparatus as set forth in claim 18 in which
said return means comprises one or more silencing tubes one end of which
is connected to one of said ports and the opposite end of which opens into
said inlet chamber.
20. Improved emission control apparatus as set forth in claim 19 in which
said housing includes an outlet chamber downstream of said another chamber
and separated therefrom by a dividing wall, said another chamber and said
outlet chamber being in fluid communication through one or more baffle
tubes projecting through said dividing wall.
21. Improved emission control apparatus as set forth in claim 20 in which
the walls of said silencing tubes and the walls of said baffle tubes are
perforated by a plurality of holes to reduce noise emitted from said
engine.
22. Improved emission control apparatus as set forth in claim 17 in which
said housing includes an outlet chamber downstream of said another chamber
and separated therefrom by a dividing wall, said another chamber and said
outlet chamber being in fluid communication through one or more baffle
tubes passing through said dividing wall, the walls of said baffle tubes
being perforated by a plurality of holes to reduce noise emitted from said
engine.
23. Improved emission control apparatus as set forth in claim 22 including
an outlet tube connected to said housing outlet and projecting therefrom
into said outlet chamber through which all gases are discharged from said
housing, the walls of said outlet tube being perforated by a plurality of
holes to further reduce noise emitted from said engine.
24. Improved emission control apparatus as set forth in claim 22 including
an inlet tube connected to said housing inlet and projecting therefrom
into said inlet chamber and through which all of said enhaust gases enter
said housing, the walls of said inlet tube being perforated by a plurality
of holes to further reduce noise emitted from said engine.
25. Improved emission control apparatus as set forth in claim 17 in which
the cross-sectional flow area of said second catalytic cell is not
substantially greater than the cross-sectional flow area of said first
catalytic cell.
26. Improved emission control apparatus as set forth in claim 25 in which
the cross-sectional flow area of said return means is less than the
cross-sectional flow area of said first catalytic cell.
27. Improved emission control apparatus as set forth in claim 25 in which
said housing is cylindrical and each of said catalytic cells is circular
in cross-section, each of said catalytic cells being surrounded by an
annular wall defining opposite ends of said intermediate chamber, the wall
surrounding said first catalytic cell having ports therethrough providing
said return means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to apparatus for use with internal
combustion engines to reduce noxious gases emitted therefrom. In
particular, the present invention pertains to apparatus particularly
suitable for use with natural gas fueled engines and for converting
nitrogen oxides, carbon monoxides and unburned hydrocarbons from the
exhaust of such engines to less noxious compounds and for reducing the
noise emitted therefrom.
2. Brief Description of the Prior Art
Silencers or mufflers for internal combustion engines have existed for many
years. Most industrial silencers utilize some type of housing in which is
mounted various types of baffles or other silencing components for
reducing the noise produced at the exhaust of an internal combustion
engine.
In addition to noise reduction, a great deal of attention has also been
directed, in recent years, to reducing the noxious gases emitted from the
exhaust of an internal combustion engine, e.g. nitrogen oxide, carbon
monoxide and other unburned hydrocarbons. As interest and concern about
pollution of the atmosphere increases, the search continues for effective
means for reducing these noxious emissions. Increased regulation by state
and federal authorities mandates that more effective means be found. The
most effective means of reducing noxious emissions at this time appears to
be those methods which utilize some type of catalyst which converts the
noxious gases to water, nitrogen, carbon dioxide and other harmless
emissions.
Most exhaust emission control apparatus of the prior art utilizes separate
devices for noise reduction and noxious gas reduction. This is probably
due to the fact that silencers or mufflers are commonly made by one
manufacturer and catalytic converters by another. Since these devices are
made separately but must be connected in series to an engine exhaust, the
pressure drop therethrough is relatively great, resulting in decreased
fuel efficiency. In addition to increased operating expense, two separate
units usually result in greater installation and maintenance costs. In
recent years, some emission control apparatus have been manufactured which
combine the functions of noise reduction and noxious gas reduction in a
single device or apparatus. Examples may be seen in U.S. Pat. Nos.
4,209,493 and 4,601,168. While these devices are substantially more
efficient and cost effective than those of the prior art, continued
concern over noise and air pollution dictates even more efficient and
effective apparatus.
SUMMARY OF THE INVENTION
The present invention provides combination noise and emission control
apparatus for use with an internal combustion engine of the type having an
enclosed housing with an inlet at one end thereof for connection with the
exhaust of an engine and an outlet at the opposite end thereof for
discharge to the atmosphere. Mounted in the housing are catalytic
converter components for reducing noxious gases emitted from the engine by
converting nitrogen oxides, carbon monoxides and unburned hydrocarbons to
less noxious compounds. Also mounted in the housing are noise reduction
components for reducing the noise emitted from the engine.
The catalytic converter components of the present invention are unique in
that two catalytic cells are transversely disposed in the housing at
spaced intervals or distances. At least part of the engine exhaust passes
through the first catalytic cell prior to passage through the second
catalytic cell and all of the engine exhaust passes through one or both of
the catalytic cells prior to being discharged from the housing outlet.
Although these catalytic cells provide a boundary between various chambers
and the housing, return areas are provided which allows some of the engine
exhaust passing through the first catalytic cell to return upstream
thereof for recirculation through the first catalytic cell. However, there
are no return areas around the second catalytic cell and all of the
exhaust gases must pass therethrough.
The noise reduction components include a number of tubular devices which
are either coaxially aligned with the housing axis or which are parallel
thereto. The walls of these tubular components are typically perforated by
a plurality of holes allowing free flow of gas therethrough. Several
arrangements are disclosed including one for industrial silencing and
another for residential quality silencing.
The combination noise and emission control apparatus of the present
invention provides noise and gas emission control in a single housing so
that some of the parts which are normally duplicated in systems utilizing
separate noise and gas emission control devices are combined for common
usage. This results in reduced installation and maintenance costs.
Furthermore, pressure drop through the emission control of the present
apparatus is much less than those which utilize separate noise and gas
emission control apparatus. This results in substantial fuel savings. Most
importantly, noise abatement and noxious gas emission reduction is
enhanced and made more effective with the apparatus of the present
invention. Many other objects and advantages of the invention will be
apparent from reading the description which follows in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal view, in section, of combination noise and
emission control apparatus according to a preferred embodiment of the
invention;
FIG. 2 is a cross-sectional view of the combination noise and emission
control apparatus of FIG. 1, taken along lines 2--2 thereof; and
FIG. 3 is a longitudinal view, in section, of combination noise and
emission control apparatus according to another preferred embodiment of
the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring first to FIGS. 1 and 2, there is shown combination noise and
emission control apparatus which includes a cylindrical housing 1 which
may actually be made of three cylindrical sections 2, 3, 4 joined at
support rings 5 and 6 by bolting, welding or any other suitable method and
closed at opposite ends by heads 7 and 8. The head 7 is provided with an
inlet 9 surrounding which is a flange 10 by which the apparatus may be
connected to the exhaust (not shown) of an internal combustion engine (not
shown). The opposite head 8 is provided with an outlet 11 surrounding
which is a flange 12. The flange 12 may be connected to a discharge pipe
(not shown) for discharge into the atmosphere or for additional handling.
Sample ports such as 13, 14 and 15 may be provided for sensing
temperature, pressure, gas analysis, etc.
Transversely disposed in the housing 1 at fixed distances from the housing
inlet 9 is a first catalytic cell 20 and, downstream thereof, a second
catalytic cell 30. These catalytic cells 20, 30 are normally made of
metallic substances and compounds which are effective in converting
nitrogen oxide, carbon monoxide and other unburned hydrocarbons to
nitrogen, carbon dioxide, water and other harmless products. The cells 20,
30 illustrated in FIGS. 1 and 2 are cylindrical cells coaxially aligned
with the axis x--x of the cylindrical housing 1. Each catalytic cell 20,
30 may be surrounded and held in place by a cylindrical containment
chamber 21, 31. Each of these chambers 21, 31 may be centrally supported
in the housing 1 by a plurality of radial support members 22, 32 which are
welded or bolted to the inside walls of the housing 1. These containment
chambers 21, 31 also support the cells 20, 30 against stress and pressure
from backfire explosions and other occurrences.
It should be noted that surrounding each catalytic cell 20, 30 is an
annular wall or partition 23, 33. Thus it can be said that the housing 1
is divided into three chambers: an inlet chamber 40, an intermediate
chamber 50 and outlet chamber 60.
As will be noted from the drawings, the annular wall 23 surrounding the
first catalytic cell 20 is provided with a plurality of ports or
passageways 24. Connected to each of these ports 24 and extending toward
the inlet end of the housing 1 is a plurality of tubular members 41, one
for each port 24. These tubular members 41 terminate at some distance from
the inlet head 7 and open into the inlet chamber 40. In addition, the
walls of each of the tubular members 41 are perforated by holes 42 which
allow exhaust gases to freely enter and exit the tubular members 41
therethrough. Structural support members 43 may aid in supporting the open
or free ends of the tubular members 41. These tubular members 41 are
sometimes referred to as internal connector silencing tubes and serve
functions for both noise reduction and noxious gas conversion that will be
more fully understood hereafter.
Centrally supported in the inlet chamber 40 is an inlet silencer/diffuser
tube 45 one end of which is connected to the inlet 9 and the opposite end
of which terminates somewhere near the midsection of the inlet chamber 40.
The walls of the silencer/diffuser tube 45 maybe perforated with a
plurality of holes 46 and may be flared outwardly from the inlet 9 toward
the first catalytic cell 20. A conical diffuser 47 may be centrally
disposed within the throat of the silencer/diffuser tube. The diffuser 47
and the flared shape of the silencer/diffuser tube 45 aides in diffusing
and distributing exhaust gases across the catalytic cell 20.
Attached to the outlet 11 and extending in a direction toward the second
catalytic cell 30 is an outlet tube 61. The walls of the outlet tube 61
are perforated by a plurality of holes 62 allowing gases to enter and exit
said tube therethrough.
In operation, exhaust gases from an internal combustion engine with which
the apparatus of the present invention is used, first flow through the
inlet 9 and silencer/diffuser tube 45 for relatively even distribution
into the inlet chamber 20. From the inlet chamber 20, at least a portion
of these exhaust gases pass through the catalytic cell 20 for conversion
into less noxious gases. Some of the gases entering the intermediate
chamber 50 return through the ports 24 and the silencing tubes 41 for
reentry into the inlet chamber 40. They are then recirculated through the
first catalytic cell 20. All of the gases eventually exit from the
intermediate chamber 50 through the second catalytic cell 30 into the
outlet chamber 60. Further conversion of the noxious gases occur through
the catalytic cell 30 and the less noxious gases and compounds eventually
exit the apparatus through the outlet tube 61 and outlet 11. It will be
noted that there are no ports or return passages surrounding the second
catalytic cell 30 so that all of the gases entering the outlet chamber 60
must exit through the outlet 11.
The operational theory of providing dual catalyst cells is that dual
catalyst cells provide more exposure surface for gas flow. In addition,
the return ports provided through the wall 23 surrounding the first
catalytic cell 20 permits recirculation of some of the exhaust gases
through the first catalytic cell. In addition, the inlet chamber 40,
intermediate chamber 50 and the silencer/diffuser tubes 41 act in
combination to suppress and reduce surges through the apparatus resulting
in the exhaust gases being in residence longer over a greater catalyst
surface. These features, along with the concomitant reduction of gas
velocity, provide a greater time of residence for the gases. This results
in substantially greater efficiency and performance with as much as
seventy percent (70%) greater emissions reduction than other designs.
Furthermore, the components of the apparatus, particularly the diffuser
47, inlet silencer/diffuser tube 45, silencing tubes 41 and outlet tube 61
result in substantial noise reduction making the apparatus especially
acceptable for industrial noise silencing and/or abatement.
Referring now to FIG. 3, an alternate embodiment of the invention will be
described which provides even greater noise reduction than the embodiment
of FIGS. 1 and 2. Many of the components of the embodiment of FIG. 3 are
similar or identical to the embodiment of FIGS. 1 and 2. These components
will be designated by the same reference numerals and many of them will
not be redescribed. In fact, the embodiment of FIGS. 1 and 2 may be easily
modified to provide the embodiment of FIG. 3. As shown, all of the
components of the apparatus of FIG. 3 from the inlet flange 10 to the
cylindrical housing section 4 may be identical to the embodiment of FIGS.
1 and 2. At this point, an additional cylindrical section 71 may be added
and provided with a head 72, outlet 73 and surrounding flange 74. An
outlet tube 75, similar to the outlet tube 61 of FIG. 1 except that it is
perhaps longer, is also provided with perforated holes 76. Additional
bracing 77 may be required.
A dividing wall 78, much like the head 8 of the apparatus of FIG. 1, is
provided to separate what was the outlet chamber 60 (now another
intermediate chamber) from a new outlet chamber 70. The chamber 60 and the
outlet chamber 70 are in fluid communication with each other through a
plurality (four in the exemplary embodiment) of baffle tubes 80. The
baffle tubes 80 are open at both ends and extend to somewhat a midpoint of
chambers 60 and 70, respectively. Support braces 81 may be provided to
maintain the parallel disposition of the baffle tubes 80. The walls of the
baffle tubes 80 may be perforated by a plurality of holes 82. The
perforated baffle tubes 80 and the lengthened outlet tube 75 serve to
further reduce noise emitted from the engine to which the apparatus is
attached.
Operation of the apparatus of FIG. 3 is essentially the same as the
apparatus of FIGS. 1 and 2, the noxious gases passing through the dual
catalyst cells 20, 30 eventually into the chamber 60. From the chamber 60,
the less noxious gases and compounds which are converted by the catalytic
cells 20, 30 pass through the baffle tubes 80 into the outlet chamber 70
and eventually exit the apparatus through the outlet tube 75. While the
conversion of noxious gases is substantially the same in the embodiment of
FIG. 3 as in the embodiment of FIGS. 1 and 2, the noise reduction
characteristics thereof are substantially better. In fact, tests have
indicated that this embodiment meets noise abatement requirements in many
residential environments.
Thus, the combination noise and emission control apparatus of the present
invention provides apparatus of greater efficiency and effectiveness than
apparatus of the prior art. Its design results in highly competitive
manufacturing and maintenance costs and more importantly results in cost
savings in fuel consumption due to less pressure drop than designs of the
prior art. Most importantly, the apparatus of the present invention
results in much improved, efficient reduction of air and noise pollution.
While two preferred embodiments of the present invention have been
described herein, many other variations can be made without departing from
the spirit of the invention. Thus, it is intended that the scope of the
invention be limited only by the claims which follow.
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